Hydrothermal Anhydrite in veins is often hydrated to gypsum by groundwater in in close proximity to-surface exposures. It is commonly linked to the minerals halite and sulfur. Gypsum is the most common sulfate mineral.[seventeen] Pure gypsum is white, but other substances discovered as impurities may give a variety of colours https://www.propanraya.com/id/produk/eco-gypsum-ee-4050